With metal cutting tools of this kind, the insert is designed to be held in a seat formed in the insert holder blade and the invention is specifically concerned with an insert holder wherein the seat is defined between a pair of jaws of the insert holder, means being provided for mechanically biasing the jaws into clamping the insert in the seat.
Usually, the insert holder blade is formed as an elongated rectangular planar element and is retained within appropriate grooves formed in the tool block and is screw clamped to the tool block.
The retaining grooves formed in the tool block can be defined within a unitary tool block or, alternatively, one of the grooves is defined within a major portion of the tool block, whilst the other groove is associated with a minor, separate portion of the tool block. Screw bolting means are provided for bolting together the two portions of the tool block and, at the same time, clamping in position the insert holder blade within the tool block. Where, as indicated above, the insert itself is retained between the insert holder jaws, the clamping of the insert holder to the tool block can at the same time be effective in biasing the jaws towards each other so as to clamp the insert between the jaws.
With such a known arrangement, i.e. where the insert is clamped within the insert holder blade and the insert holder is clamped within the tool block by one and the same bolt clamping means, every time that an insert has to be replaced the bolt clamping means is loosened, thereby allowing for the removal and replacement of the insert. At the same time, however, the insert holder blade itself is loosened within the tool block and, upon replacement of the insert, the holder blade must be re-positioned so as to ensure the correct positioning thereof vis a vis the tool block and in consequence, the correct positioning of the insert.